A Revolution in the "Heart" of Automobiles--Research and Development Status of Gasoline Direct Injection Engines
In the face of increasingly stringent regulations on vehicle exhaust emissions, it is time for conventional gasoline engines to be withdrawn from the historical stage. With the advent of gasoline direct injection technology, the development of gasoline engines has entered a new era and is expected to replace traditional gasoline engines. And diesel engines become the ideal driving force for future cars.
1. The superior performance of gasoline direct injection engines, abbreviated as GDI, is a hot topic in the research and development of foreign internal combustion engine technologies in recent years. The traditional gasoline engine injects gasoline into the intake pipe and mixes with air before entering the cylinder. The GDI engine directly injects gasoline into the cylinder. The gas atomization in the cylinder and the surface of the piston form a mixture with air. Burning. Compared with the conventional gasoline engine, GDI has a good job stability, while the low temperature start has been significantly improved, stratified combustion can be achieved, fuel economy is greatly improved, its fuel consumption can reach turbocharged direct injection (TDI) diesel engine Level and omitting the turbocharger eliminates complicated high pressure injection systems. The GDI engine can use lean burn technology, with an air-fuel ratio of up to 40 or even up to 100:1, making the power and torque higher than traditional gasoline engines, with lower fuel consumption, noise, and carbon dioxide emissions. The homogeneity, transient response and startability of the GDI engine are greatly improved compared with the traditional gasoline engine. With the continuous maturation and improvement of the gasoline direct injection technology, other superior performances will be further demonstrated and the development potential is still great. . Therefore, all countries are vigorously developing GDI engines with advanced technology and excellent performance.
Second, the development of gasoline direct injection engine Gasoline direct injection engine can be described as blooming in Germany, but they are familiar with Japan. As far back as the 1950s, there were direct-injection two-stroke gasoline engines in Germany and even on the prestigious SL-Class sedan. However, due to the poor running performance of the engine at that time, the car was almost impossible to open, and the exhaust gas problem was also serious. Soon disappeared. Later, Mitsubishi Motors Japan successfully developed the GDI engine in 1996 and installed it on the Japanese auto market in August of the same year. In 1997, the same engine was used to enter the Western European market. The displacement of the engine was 1.8L, the power was 88kW, and the fuel consumption per 100km was about 5L. Mitsubishi plans to convert all of its gasoline engines into petrol direct injections in recent years. Mitsubishi's success shows that gasoline direct injection is feasible, and the problem of high NO in exhaust gas can be solved by using exhaust gas recirculation and adding catalytic cracking conversion devices.
Compared with conventional indirect-jet gasoline engines, GDI has made great strides both in terms of fuel consumption and exhaust gas purification, and in terms of lean combustion, GDI engines allow the mixture to become thinner, especially at part-load conditions. The theoretically calculated standard air-fuel ratio should be 15:1. Both Toyota and Mitsubishi have achieved preliminary results in the lean-burn technology. The air-fuel ratio has reached 20:1, but the mixture can be further diluted if direct gasoline injection is used. . Usually the intake port is more or less horizontal, and Mitsubishi's GDI engine successfully builds a layered charge in the combustion chamber through the vertically-arranged intake port and a specially designed nose piston, near the spark plug. In the area, a thicker oil mist is formed, that is, a mixture that can catch fire. In other areas, there is no mixture of gases. Therefore, even if the air-fuel ratio is 40:1, the engine can reliably catch fire. When the throttle is maximum, the air-fuel mixture approaches the standard air-fuel ratio, and the advantages of fuel economy disappear. However, vehicles rarely work under full-load conditions.
The successful development of the Mitsubishi GDI engine has set off a worldwide boom in research and development. The development of the gasoline engine has taken a new step and will promote the development of the global automotive industry.
3. Development Status of Gasoline Direct Injection Engines The development and utilization of GDI engines are currently the world's leading position for Mitsubishi. When automakers began investing heavily in fuel cells and other alternative fuels for automobiles, Mitsubishi was confident that it could further develop its direct injection technology. Although Japanese automakers are also working on fuel cell technology, Mitsubishi believes it will be displayed in 1996. Gasoline direct injection technology is a long-term effective technology rather than a temporary technology. A senior official in charge of product research and development at Mitsubishi Electric Corporation stated that the fuel cell has its own location and we are using it in a suitable vehicle. This super reliability and super clean gasoline direct injection technology will be favored in the future. .
In 1997, Mitsubishi also developed three models of the 2.4L four-cylinder machine, the 3.0L six-cylinder machine and the 3.5L six-cylinder machine, which were installed on four medium- and large-sized cars. In 2000, three new GDI engines were introduced: the 0.66L inline triple-cylinder, the 1.5L inline four-cylinder and the 4.5L V8. According to Mitsubishi's tests on the 1.8LGDI engine, compared with conventional gasoline engines, this model can save 20% fuel, reduce emissions by 20%, and increase engine power. At the Frankfurt Motor Show in September 1999, the company had four Two of the concept cars debuted on the stage. Although the details of the show were still in the secrecy phase, Mitsubishi hopes that the two concept cars will become models of urban vehicles. One of them represents the latest achievements of Mitsubishi's GDI-Sigma series of power technologies, demonstrating this epoch-making automotive internal combustion engine technology. The company recently announced in Japan that GDI-Sigma direct injection combustion engine has a series of relevant latest technologies such as: continuously variable transmission technology, idle hybrid power, and low-cost turbocharging technology. As a result, the economic efficiency of the car is higher than that of the current According to the results of Mitsubishi's GDI launch, due to the presence of conventional engines and automatic transmissions, the car has been plagued by problems such as drive belt friction loss, torque conversion power loss, vehicle vibration, and low fuel efficiency, and GDI-Sigma gasoline engine The integrated control and transmission make these problems solved. GDI engines can provide greater torque output and more reliable combustion. They match engine power with different hydraulic pressures, which can reduce fuel waste due to belt slip caused by high torque when pressure changes. Tests used in urban areas show that multi-inlet gasoline injection engine idle consumption accounts for 16% of fuel energy, while in GDI engines this loss can be reduced to 10%, and the vehicle can reduce energy consumption from rest to restart. In addition, the system also features fast start-up. Mitsubishi developed a hybrid vehicle equipped with GDI. By providing a simple hybrid system (a car engine and a battery), GDI can start and accelerate within 0.1 s. Mitsubishi's two-stage hybrid patent produces higher compression rates, and the ultra-lean combustion of turbine engines provides higher power.
Toyota also successfully developed the D-4 2.0LGDI engine at the end of 1996, and it has been put into use in batches. In 1998, the company developed 1.6L and 1.8L GDI engines, followed by a new 2.0L GDI engine in 1999. According to Toyota’s tests on the D-4 GDI engine, the machine can reduce fuel consumption by 30% and increase power by 10%. Nissan developed the 3.0L and 2.5L V6 machines, and Fuji Heavy Industries’ 2.5L horizontal four-cylinder machines and Honda 1.0L inline three-cylinder machine will also be listed after 2000.
The four-stroke GDI engine developed by Chrysler Automotive has improved fuel economy by 20% to 30%, which is comparable to that of a small-displacement, direct-injection diesel engine. After an in-depth study of the GDI engine, Ford found that the GDI engine has further improved thermal efficiency. And power potential.
After the GDI engine developed by Volkswagen AG was well received at the 1997 Frankfurt Motor Show, Audi also exhibited a 1.2-liter three-cylinder GDI engine. Mercedes-Benz had invested 100 million Deutsche Marks as early as the end of 1997 to carry out GDI research projects in full. The company plans to launch GDI engines in 2001 or 2002, and believes that European-equipped GDI engines can meet the latest requirements of European regulations for emission standards.
At present, gasoline direct-injection engines have attracted the attention of major automobile manufacturers in the world and they have joined the ranks of research and development. With the advent of the 21st century, GDI engines will be exposed in automotive power plants.
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